Custom cypress commands is not assignable to parameter of type 'keyof Chainable<any>

Question

In a .ts file I create a test to try and access a custom created command from command.js, createInbox function is underlined with red with the following message : Property 'createInbox' does not exist on type 'cy & EventEmitter

it.only('dsdsds', () => {
    cy.createInbox().then((inbox) => { 
      console.log(inbox);
      // { id: '...', emailAddress: '...' }
    });
  })

My command.js file look like this

const { MailSlurp } = require("mailslurp-client");
const mailslurp = new MailSlurp(Cypress.env("mailSlurpApiKey"));

Cypress.Commands.add("createInbox", () => {
  return mailslurp.createInbox();
});

Cypress.Commands.add("waitForLatestEmail", (inboxId) => {
  return mailslurp.waitForLatestEmail(inboxId);
});

I understand that I have to rename command.js to ts, however when I do that all custom commands is underlined with red with the following error : Argument of type '"waitForLatestEmail"' is not assignable to parameter of type 'keyof Chainable

How could I fix this?

Answer 1

Solved by adding custom chainable interface to support folder

declare namespace Cypress {
  interface Chainable {
    createInbox(): Chainable<any>;
    waitForLatestEmail(inboxId: number): Chainable<any>;
  }
}